The present invention relates to a conductive member to be used inside of a disk drive such as a hard disk.
In recent years, a hard disk has been progressively reduced in size, and accordingly, various kinds of members to be used inside of the hard disk also have been progressively reduced in size and thickness.
For example, a magnetic head assembly for reading and writing data from and on a magnetic medium in a hard disk includes a magnetic head and a preamp pre-amplifying circuit, which is electrically connected to the magnetic head and amplifies a signal read by the magnetic head. The magnetic head and the preamp pre-amplifying circuit are made of a conductive member called an inter-connect (i.e., an integrated lead suspension abbreviated as “an ILS”).
The conductive member includes a metal layer serving as a back side (i.e., a back side metal layer), a polyimide layer formed at either surface of the metal layer (i.e., an insulating layer), and a conductive wire formed on the polyimide layer. A substantially rectangular pad is formed on a side, of the conductive wire, for connection to the preamp pre-amplifying circuit. The pad is introduced to a position perpendicular to the plane of a flexible substrate having the preamp pre-amplifying circuit mounted thereon, and further, is electrically connected to a terminal on the side of the flexible substrate by using a conductive material such as a solder.
Patent Literature 1 (Japanese Patent Laid-open No. 2002-9203) discloses the technique of forming an insulating layer on a wiring board for use in the above-described hard disk or the like.
Moreover, Patent Literature 2 (Japanese Patent Laid-open No. 2003-152404) discloses the technique of forming a back side metal layer so as to reduce a transmission loss in a transmission line.
Patent Literature 2 discloses that a line loss is reduced by forming a hole at the back side metal layer right under a conductive wire. The hole is formed across two conductors so as to enhance differential transmission characteristics of the transmission line.